Well by the looks of it, either the owner of the site, hasn't uploaded any pages for the site.
Or maybe he's just stupid and, by the look's of things, any skiddie with a Brute Forcer and a default password file, and the now how can gain access to the cpanel for the site..

But the prompt that you are coming across, is just a login mechanism, so that you need the correct crodentials to enter into the cpanel.
It's pretty much just like the login screen when you boot up windows.
It asks you for your
Username:
Password:

And once you type in the relevan information it will take you to your Desktop.
But with this login screen, when you login it will take you to the Control Panel of the site, you can set up email addresses, upload, download, set up MySQL databases. etc etc

So that is why you run into that prompt.


cheers
front2back:.